Perforating guns have traditionally been used to stimulate production from a formation once the well has been drilled. Perforating guns have also been used in existing wells previously on production from a particular zone to initiate production from other zones within the wellbore.
If the well is pressurized, one technique that has been used to facilitate perforation at a given depth is to kill the well with heavy fluids prior to the perforating procedure. However, the technique of killing the well is thought to be undesirable in that it may adversely affect the future performance of the well from the zone to be perforated. The alternative to killing the well is to run the perforating guns into the wellbore in a live condition. To do this requires an assembly of rams and blowout preventers, used in conjunction with an elongated housing that facilitates insertion and removal of downhole tools in the wellbore as well as the tubing, commonly known as a lubricator.
Sometimes the string of guns can be quite lengthy, well in excess of the general length of a lubricator, which is approximately 60 feet. The guns themselves are generally in the order of about 15 feet long and are stacked above the other and spaced accordingly so that when they are spotted below, the perforation will occur at the proper locations and intervals. One of the concerns that has arisen in the past with stacking perforating guns and inserting them through a lubricator is the connections that have been available. In the past, some sort of rotation has generally been required to connect one gun to the other when putting them in a string of guns. This has created complexities required of the lubricator, as well as various hydraulic supplies which have been required to be connected to the lubricator to initiate the required rotation to connect one gun to the other while in the lubricator. Accordingly, one of the objectives of the present invention is to present a connection technique which requires no rotation and can be easily accomplished by merely setting down weight With this objective accomplished, the lubricator employed can be far simpler and it can be set up quicker; but most importantly, the integrity of the joints is far greater when the uncertainties of combined movements are removed for connection of one gun to another.
Another problem that can arise in trying to remove guns after firing from a live well is the potential for leak paths through the fired guns internally thereof. Thus, another object of the invention is to provide connectors which will allow for reliable external sealing around the fired guns for the removal process, while, at the same time, sealing off any internal leak paths, thus allowing for effective well control during the removal operation. The configuration of the connectors is also such that when properly supported by a hanging and seal ram (hereinafter "seal ram"), a section of the connector is presented opposite a shear ram where that section has no explosives. Accordingly, another object of the invention is to present a zone of the connector opposite the shear ram so that if an emergency situation develops, the shear ram does not need to cut through a zone having explosives which could create an extremely dangerous situation at the surface. Yet another objective of the present invention is to provide for easy connection and disconnection between perforating guns. Those and other objectives of the invention will become more apparent after review of the detailed description of the preferred embodiment below.